If you're playing around with Snappy and Ubuntu Core, the new transaction based packaging platform in town, and receive the following error:

ImportError: No module named 'click.repository'

It's most likely because you also have the ubuntu-sdk PPA installed, and a new version of python3-click has been pushed up that doesn't include the repository submodule that Snappy uses. I found unravelling the two project's dependencies to be non-trivial at the moment, so here's an alternative quick fix:

1. sudo apt purge -y python3-click

2. Create a new file at /etc/apt/preferences.d/snappy-ppa-1500, with these contents (telling apt that we prefer duplicate packages from the snappy-dev PPA).

3. sudo apt update

4. sudo apt install -y --force-yes snappy-tools

For the time being this should select the packages we need from the snappy-dev PPA, and giving us the right python3-click, complete with repository submodule.

The other alternative is to confine your Snappy experiments to an LXC or VM; or completely purge both PPAs and all the packages from them and reinstall just Snappy if you don't care about Ubuntu Touch or regular click package dev right now.
I'm sure the conflict will be fixed soon though. :-)